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Slow variables that shape bushfire resilience

Creating the perfect firestorm on the BBC writes about two of the slow variables that produce a fire situation: climate and fuel accumulation:

Current climate projections point to an increase in fire-weather risk from warmer and drier conditions.

Two simulations used by Australia’s lead scientific agency, CSIRO, and the Australian Bureau of Meteorology point to the number of days with very high and extreme fire danger ratings increasing by some 4-25% by 2020, and 15-70% by 2050.

The agencies’ Climate Change in Australia report cites the example of Canberra which may be looking at an annual average of 26-29 very high or extreme fire danger days by 2020 and 28-38 days by 2050.

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Left to its own devices, Nature will initiate – usually through lightning strikes – regular “cool fires” which burn out grasses and shrubs but leave trees charred though not destroyed.

Humans, if they want to live in these types of locations, have to learn to manage their surroundings.

Principally, this means not letting the undergrowth build up, to provide the “ladder” that would otherwise allow fires to consume trees, also. In such circumstances, cool fires rapidly become very hot – and very destructive – ones.

It is why authorities in fire-prone districts across the world – not just in Australia – will practise back-burning, or the controlled ignition of undergrowth.

This type of management is not always popular. Residents dislike being smoked out of their homes every time it is done and some people will resent having the pleasant view from the porch turned to a blackened mess.

There is a natural fear also that such burning might get out of hand and result in the kind of damage it is trying to prevent.

But the consequences of attempting to work against Nature, by trying to prevent any fires at all, can be catastrophic.

David Packham, who has studied bushfires and meteorology for many decades, said at the weekend that Australia had ignored the warnings on this for far too long; and that Victoria was paying the price for allowing fuel loads to build up to unprecedented levels.

“The mismanagement of the south-eastern forests of Australia over the last 30 or 40 years by excluding prescribed burning and fuel management has led to the highest fuel concentrations we have ever had in human occupation,” said the researcher from the Climatology Group at the School of Geography & Environmental Science, at Monash University.

“The state has never been as dangerous as what it is now and this has been quite obvious for some time.”

How vulnerable people are who live in these areas in another important factor in how dangerous these fires are. Not just the number of people, but their landscape management, their lot management, and their house construction – as well as their fire prediction and warning system. What seems clear now is that people were predicting severe fires in Victoria, but that these general warnings didn’t result in specific actions, but when specific fires appeared they moved quicker than the warning systems could respond.